Examples of nonvolatile memories using resistance materials include phase-change random access memories (PRAMs), resistive RAMs (RRAMs), and magnetic RAMs (MRAMs). While dynamic RAMs (DRAMs) or flash memories store data using charges, nonvolatile memories using resistance materials store data using a state change of a phase-change material such as chalcogenide alloy (in the case of PRAMs), a resistance change of a variable resistance material (in the case of RRAMs), or a resistance change of a magnetic tunnel junction (MTJ) thin film according to a magnetization state of a ferromagnetic material (in the case of MRAMs).
Semiconductor products are increasingly becoming smaller in volume but are required to process high-volume data. Therefore, it may be required to increase the operation speed and integration density of memory devices used in these semiconductor products. To meet these demands, an MRAM which implements a memory function using a change in resistance with respect to a change in the polarity of a magnetic material has been suggested and is being intensively researched.